1. Field of the Invention
The present invention relates to protective bellows and, more particularly, to the cuff configuration of a protective bellows.
2. Description of the Prior Art
Protective bellows have been used for a period of years to protect various extensible devices, such as linear actuators, industrial components and automotive components. Within the field of automotive components, protective bellows are used primarily with shock absorbers, MacPherson struts, steering dampers and the like.
Economy of manufacture is always a prime criterion for any product. This is particularly true for relatively low cost high volume products. Within the field of automotive components, the items to be protected vary in travel length required and configuration and size attendant the opposed ends of the bellows. For a manufacturer, it is costly to manufacture a protective bellows for each product of a line of products unless the number of same size bellows is very large. Similarly, for a supplier, it is costly in terms of shipping, storage and handling to maintain a large inventory of differently sized protective bellows. These increased costs ultimately must be borne by the end user or consumer to his detriment.
With respect to a protective bellows, there are three components which affect the universality or genericness of the device. These are travel, top attachment mechanism and bottom attachment mechanism. With regard to shock absorbers, manufacturers have generally agreed to install a fixed size washer on the plunger of the shock absorber at the point at which the protective bellows, or boot, as it is commonly referred to, is attached. Hence, one end of the boot, no matter what the remaining parts may be like, is generally standardized.
The question of travel, compression and expansion, of the boot, can be accommodated within a specific range or ranges through careful selection of the number of bellows and their respective interior and exterior diameters. Accordingly, a small number of families of bellows size will accommodate substantially all shock absorber installations with respect to top end attachment and length of travel.
The diameter of a cylinder or "can", as it is referred to, of a shock absorber can vary in size from approximately 13/4 inches to approximately 23/8 inches. A boot is made of resilient elastic material and the lower end, or cuff can be stretched to a certain extent to accommodate, within the range of stretch, certain can diameters. Since the material of which boots are generally made, a stretch greater than 5% is beyond the norm. This limitation of materials necessitates the manufacture and stocking of a plurality of families of shock absorber boots having different sized cuffs. One solution to assist in stretching a cuff has been that of slitting the cuff. Such slitting is generally not considered an acceptable solution from an engineering standpoint; stresses imposed upon the boot may result in rapid tearing and deterioration.
Because the boot compresses and expands in response to elongation and shortening of the device protected, the volume of air within the bellows may change rapidly and substantially. Venting of the bellows must therefore be accommodated. Such venting is often done by punching a hole in the bellows. This is an inelegant solution and also requires additional expense during either manufacture or installation.